Mapping long-period soil resonances in the Kathmandu basin using microtremors

This study reports the geostatistical analysis of a set of 40 single-station horizontal-to-vertical spectral ratio (HVSR) passive seismic survey data collected in the Kathmandu basin (Nepal). The Kathmandu basin is characterized by a heterogeneous sedimentary cover and by a complex geo-structural setting, inducing a high spatial variability of the bedrock depth. Due to the complex geological setting, the interpretation and analysis of soil resonance periods derived from the HVSR surveys is challenging, both from the perspective of bedrock depth estimation as well as of seismic-site effects characterization. To exploit the available information, the HVSR data are analyzed by means of a geostatistical approach. First, the spatial continuity structure of HVSR data is investigated and interpreted taking into consideration the geological setting and available stratigraphic and seismic information. Then, the exploitation of potential auxiliary variables, based on surface morphology and distance from outcropping bedrock, is evaluated. Finally, the mapping of HVSR resonance periods, together with the evaluation of interpolation uncertainty, is obtained by means of kriging with external drift interpolation. This work contributes to the characterization of local seismic response of the Kathmandu basin. The resulting map of soil resonance periods is compatible with the results of preceding studies and it is characterized by a high spatial variability, even in areas with a deep bedrock and long resonance periods

Shaking Scenarios from Multiple Source Models Shed Light on the 8 September 1905 Mw 7 Calabria Earthquake (Southern Italy)

4noThe earthquake (Mw 7) that struck western Calabria (southern Italy) on 8 September 1905 profoundly struck a broad region, causing 557 deaths, injuring more than 2000 people, and leaving about 300,000 people homeless. Historical documents also reported a tsunami, although not devastating, for which effects were observed both along the coast and offshore. For all the damage it caused, this event was much studied but not fully explained. Literature source models for the 1905 earthquake are numerous and diverse, in fault geometry, location, and even associated magnitude. They also differ in nature, because these solutions are either field-based or derived from tsunami modeling and macroseismic data inversion. Above all, few or none of the previously published source models appear to be fully compatible with the damage pattern caused by this earthquake. To contribute to the identification of the seismogenic source of this destructive event, we computed a series of ground-shaking scenarios based on the different fault-source models that various authors associated with this event. The only documented data available that are suitable for our comparative purposes are the macroseismic intensities associated with localities affected by the event. Our results show that shaking scenarios for two out of seven literature source models are compatible with the damage distribution caused by the 1905 earthquake. The different parameters and boundary conditions constraining these two solutions suggest that either seismogenic source should include further complexities. Alternatively, because these two sources are antithetic and partially form a graben, they might have kinematically interacted, if passively, on 8 September 1905. Also, our critical analysis attempts to take site effects into account, at least qualitatively, allowing a more robust evaluation of damage distribution against numerical models.openembargoed_20160430Sandron, Denis; Loreto, Maria Filomena; Fracassi, Umberto; Tiberi, LaraSandron, Denis; Loreto, Maria Filomena; Fracassi, Umberto; Tiberi, Lar

Rapid estimation of the seismic impact through the active contribution of the civil protection volunteers

Immediately after an earthquake, a rapid estimation of the seismic impact is crucial to carrying out a prompt and appropriate Civil Protection response. This is particularly important in districts characterized by frequent and moderate-to-high seismicity, as is the case in the north-eastern part of Italy. In this paper, the authors illustrate an innovative approach developed in the Friuli Venezia Giulia Region (in north-eastern Italy), based on the active contribution of Civil Protection volunteers. The methodology is based on the rapid and pre-codified communication of the earthquake effects, focusing on two main aspects: (i) the observed effects on people and buildings in the urban areas, and (ii) the structural and non-structural damage observed on pre-identified buildings. In particular, this paper illustrates the methodology and its integration into the seismic emergency plans of the municipalities in the Friuli Venezia Giulia Region and discusses the first test, which occurred during a full-scale exercise and on the occasion of recent minor earthquakes affecting the area. \ua9 2016-OGS

In Search of New Imaging For Historical Earthquakes: A New Geophysical Survey Offshore Western Calabria (Southern Tyrrhenian Sea, Italy)

During the summer of 2010 we carried out a survey to acquire a multidisciplinary dataset within the Gulf of Sant'Eufemia (SE Tyrrhenian sea, Italy), with the aim of studying the active tectonics affecting the region, including that potentially responsible for key, elusive earthquakes such as the to-date unexplained 8 September 1905 (Mw 7 - 7.5) earthquake. The data here analysed highlight the presence of several tectonic and morphologic features characterizing the investigated area. We have recognized the Angitola Channel, a deep and wide canyon showing a straight trend in its coastward segment, and a meandering trend in the seaward segment. Based on morpho-structural elements, we maintain that the Angitola Channel could be tectonically controlled. Moreover, several gravitational instabilities as slumps and collapses affect the flanks of the morpho-structural high, detected offshore Capo Vaticano. Very high resolution seismic data have unveiled the presence of numerous fluid escape features and several mud volcanoes straddling the sector from the coastline to seaward.INOGS (RIMA Department) supported the acquisition of the entire dataset.Published385-4013.2. Tettonica attivaJCR Journalrestricte

The leading digit distribution of the worldwide Illicit Financial Flows

Benford's law states that in data sets from different phenomena leading digits tend to be distributed logarithmically such that the numbers beginning with smaller digits occur more often than those with larger ones. Particularly, the law is known to hold for different types of financial data. The Illicit Financial Flows (IFFs) exiting the developing countries are frequently discussed as hidden resources which could have been otherwise properly utilized for their development. We investigate here the distribution of the leading digits in the recent data on estimates of IFFs to look for the existence of a pattern as predicted by Benford's law and establish that the frequency of occurrence of the leading digits in these estimates does closely follow the law.Comment: 13 pages, 10 figures, 6 tables, additional data analyi

Seismic hazard for the Trans Adriatic Pipeline (TAP). Part 2: broadband scenarios at the Fier Compressor Station (Albania)

AbstractTo ensure environmental and public safety, critical facilities require rigorous seismic hazard analysis to define seismic input for their design. We consider the case of the Trans Adriatic Pipeline (TAP), which is a pipeline that transports natural gas from the Caspian Sea to southern Italy, crossing active faults and areas characterized by high seismicity levels. For this pipeline, we develop a Probabilistic Seismic Hazard Assessment (PSHA) for the broader area, and, for the selected critical sites, we perform deterministic seismic hazard assessment (DSHA), by calculating shaking scenarios that account for the physics of the source, propagation, and site effects. This paper presents a DSHA for a compressor station located at Fier, along the Albanian coastal region. Considering the location of the most hazardous faults in the study site, revealed by the PSHA disaggregation, we model the ground motion for two different scenarios to simulate the worst-case scenario for this compressor station. We compute broadband waveforms for receivers on soft soils by applying specific transfer functions estimated from the available geotechnical data for the Fier area. The simulations reproduce the variability observed in the ground motion recorded in the near-earthquake source. The vertical ground motion is strong for receivers placed above the rupture areas and should not be ignored in seismic designs; furthermore, our vertical simulations reproduce the displacement and the static offset of the ground motion highlighted in recent studies. This observation confirms the importance of the DSHA analysis in defining the expected pipeline damage functions and permanent soil deformations

Benford's law predicted digit distribution of aggregated income taxes: the surprising conformity of Italian cities and regions

The yearly aggregated tax income data of all, more than 8000, Italian municipalities are analyzed for a period of five years, from 2007 to 2011, to search for conformity or not with Benford's law, a counter-intuitive phenomenon observed in large tabulated data where the occurrence of numbers having smaller initial digits is more favored than those with larger digits. This is done in anticipation that large deviations from Benford's law will be found in view of tax evasion supposedly being widespread across Italy. Contrary to expectations, we show that the overall tax income data for all these years is in excellent agreement with Benford's law. Furthermore, we also analyze the data of Calabria, Campania and Sicily, the three Italian regions known for strong presence of mafia, to see if there are any marked deviations from Benford's law. Again, we find that all yearly data sets for Calabria and Sicily agree with Benford's law whereas only the 2007 and 2008 yearly data show departures from the law for Campania. These results are again surprising in view of underground and illegal nature of economic activities of mafia which significantly contribute to tax evasion. Some hypothesis for the found conformity is presented.Comment: 18 pages, 5 tables, 4 figures, 61 references, To appear in European Physical Journal